The present invention and improvement over co-pending applications, Ser. No. 654,299 filed Feb. 2, 1976 and Ser. No. 790,890 filed May 28, 1976 of the same inventor, provides further simplified and improved circuitry for selectively positioning the spark. The inventor further provides an improved ignition coil design having a short constant time dwell providing secondary voltage of 48 to 50 KV from a 12 volt system over a potential operating range of from idle to 12,000 RPM of an 8 cylinder engine while providing approximately 20 engine degrees of electronic spark advance.
Most ignition systems of the inductive type use a constant angle of rotation to provide dwell. As a result, at slow speeds, excessive current is used with resultant heating, while at speeds in excess of 2,500 RPM, there is insufficient dwell time to saturate the ignition coil core so that the secondary output voltage drops off appreciably.
U.S. Pat. Nos. 3,937,193 and 3,938,490 disclose methods providing limited periods of constant dwell time but still draw excessive current at low speeds and provide low secondary voltage at high speeds.
A multitude of other patents have issued which disclose various methods of providing solid state spark position circuitry but none of them use the alternating voltage generated directly by a magnetic pickup coil to provide a method of positioning the spark.
The Chrysler Corporation is currently building a spark positioning system based on U.S. Pat. Nos. 3,885,534 and 3,910,243 where the magnetic pickup signal is converted to a sawtooth pulse which is then utilized to provide spark advance. No attempt has been made to provide a constant dwell.
In accordance with the invention disclosed, a novel high-voltage distribution system is provided using a conventional diameter distributor cap of 37/8 inches for an 8 cylinder engine capable of distributing sparks in excess of 40 KV to the spark plugs while using full electronic spark advance. Delco Remy found it necessary to increase the diameter of the distributor cap on current distributors for 8 cylinder engines, to 53/8 inches when providing voltages of up to 35 KV with mechanical spark advance. In Applicant's co-pending application, Ser. No. 654,299, filed Feb. 2, 1976, a method of distributing spark voltages in excess of 40 KV is disclosed while providing full electronic advance using a novel rotor responsive to speed in a distributor cap diameter of 53/8 inches.